pwm: pwm-tiehrpwm: Low power sleep support

In low power modes of AM33XX platforms, peripherals power is cut off.
This patch supports low power sleep transition support for EHRPWM
driver.

Signed-off-by: Philip Avinash <avinashphilip@ti.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>

drivers/pwm/pwm-tiehrpwm.c

@@ -113,20 +113,37 @@
 
 #define NUM_PWM_CHANNEL		2	/* EHRPWM channels */
 
+struct ehrpwm_context {
+	u16 tbctl;
+	u16 tbprd;
+	u16 cmpa;
+	u16 cmpb;
+	u16 aqctla;
+	u16 aqctlb;
+	u16 aqsfrc;
+	u16 aqcsfrc;
+};
+
 struct ehrpwm_pwm_chip {
 	struct pwm_chip	chip;
 	unsigned int	clk_rate;
 	void __iomem	*mmio_base;
 	unsigned long period_cycles[NUM_PWM_CHANNEL];
 	enum pwm_polarity polarity[NUM_PWM_CHANNEL];
 	struct	clk	*tbclk;
+	struct ehrpwm_context ctx;
 };
 
 static inline struct ehrpwm_pwm_chip *to_ehrpwm_pwm_chip(struct pwm_chip *chip)
 {
 	return container_of(chip, struct ehrpwm_pwm_chip, chip);
 }
 
+static u16 ehrpwm_read(void *base, int offset)
+{
+	return readw(base + offset);
+}
+
 static void ehrpwm_write(void *base, int offset, unsigned int val)
 {
 	writew(val & 0xFFFF, base + offset);
@@ -516,11 +533,77 @@ static int ehrpwm_pwm_remove(struct platform_device *pdev)
 	return pwmchip_remove(&pc->chip);
 }
 
+void ehrpwm_pwm_save_context(struct ehrpwm_pwm_chip *pc)
+{
+	pm_runtime_get_sync(pc->chip.dev);
+	pc->ctx.tbctl = ehrpwm_read(pc->mmio_base, TBCTL);
+	pc->ctx.tbprd = ehrpwm_read(pc->mmio_base, TBPRD);
+	pc->ctx.cmpa = ehrpwm_read(pc->mmio_base, CMPA);
+	pc->ctx.cmpb = ehrpwm_read(pc->mmio_base, CMPB);
+	pc->ctx.aqctla = ehrpwm_read(pc->mmio_base, AQCTLA);
+	pc->ctx.aqctlb = ehrpwm_read(pc->mmio_base, AQCTLB);
+	pc->ctx.aqsfrc = ehrpwm_read(pc->mmio_base, AQSFRC);
+	pc->ctx.aqcsfrc = ehrpwm_read(pc->mmio_base, AQCSFRC);
+	pm_runtime_put_sync(pc->chip.dev);
+}
+
+void ehrpwm_pwm_restore_context(struct ehrpwm_pwm_chip *pc)
+{
+	ehrpwm_write(pc->mmio_base, TBPRD, pc->ctx.tbprd);
+	ehrpwm_write(pc->mmio_base, CMPA, pc->ctx.cmpa);
+	ehrpwm_write(pc->mmio_base, CMPB, pc->ctx.cmpb);
+	ehrpwm_write(pc->mmio_base, AQCTLA, pc->ctx.aqctla);
+	ehrpwm_write(pc->mmio_base, AQCTLB, pc->ctx.aqctlb);
+	ehrpwm_write(pc->mmio_base, AQSFRC, pc->ctx.aqsfrc);
+	ehrpwm_write(pc->mmio_base, AQCSFRC, pc->ctx.aqcsfrc);
+	ehrpwm_write(pc->mmio_base, TBCTL, pc->ctx.tbctl);
+}
+
+static int ehrpwm_pwm_suspend(struct device *dev)
+{
+	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
+	int i;
+
+	ehrpwm_pwm_save_context(pc);
+	for (i = 0; i < pc->chip.npwm; i++) {
+		struct pwm_device *pwm = &pc->chip.pwms[i];
+
+		if (!test_bit(PWMF_ENABLED, &pwm->flags))
+			continue;
+
+		/* Disable explicitly if PWM is running */
+		pm_runtime_put_sync(dev);
+	}
+	return 0;
+}
+
+static int ehrpwm_pwm_resume(struct device *dev)
+{
+	struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < pc->chip.npwm; i++) {
+		struct pwm_device *pwm = &pc->chip.pwms[i];
+
+		if (!test_bit(PWMF_ENABLED, &pwm->flags))
+			continue;
+
+		/* Enable explicitly if PWM was running */
+		pm_runtime_get_sync(dev);
+	}
+	ehrpwm_pwm_restore_context(pc);
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(ehrpwm_pwm_pm_ops, ehrpwm_pwm_suspend,
+		ehrpwm_pwm_resume);
+
 static struct platform_driver ehrpwm_pwm_driver = {
 	.driver = {
 		.name	= "ehrpwm",
 		.owner	= THIS_MODULE,
 		.of_match_table = ehrpwm_of_match,
+		.pm	= &ehrpwm_pwm_pm_ops,
 	},
 	.probe = ehrpwm_pwm_probe,
 	.remove = ehrpwm_pwm_remove,